The invention relates generally to the field of hand sharpening tools and more particularly to a hand held device for sharpening tools and instruments having single cutting edge type blades such as lawnmowers and the like.
As most people are aware, there are and have been a great variety of sharpening devices available for home, business, commercial and industrial uses, ranging from complicated and expensive grinders to simple home-type sharpeners. With sharpeners used for blades which have only one cutting edge, as for example lawnmowers, it is necessary to remove the blade from the mower so that it can be sharpened by the age old methods of grinder wheels or files. Thus, the sharpening chore is tedious and time-consuming. If in fact such sharpeners are not available, as for instance with scissors, then the owner must take them to a professional. What is true of lawnmowers and scissors is also true of tin snips, hedge trimmers, some sickles, blades for sawmill chippers, hand and electric grass trimmers. The feature which all of the above-identified tools have in common is that the cutting blades are sharpened on one side only. So far as applicant is aware, there is no tool on the market which is hand held and which can sharpen a blade such as for a lawnmower without removing the blade.
In any event, whether the device is hand held or whether it is bench mounted, they do become dull and must be periodically sharpened or they become useless.
The U.S. Patent to Heinmiller U.S. Pat. No. 3,149,506 is a sharpener for knives and tool bits and for deburring. The design of the patented device is such that it is intended for a different kind of operation and thus in principle and structure is significantly different.